Partial and Total Solvent-Free Limonene’s Hydrogenation: Metals, Supports, Pressure, and Water Effects

Table 6

Hydrogenation of cymene (2.75 MPa, rt) to menthane.

Metal	Support	Conversion (%)	Cis/Trans(%)	Time (h)	TOF (h^−1)^a
Pd	Carbon^b	5	35/65	24	0.2
		0	—	24	—
	Silica^c	0	—	24	—
Pt	Carbon^d	94	68/32	24	11
		85	58/42	24	10
	Silica^e	79	61/39	24	9
Ru	Carbon^d	100	65/35	5	30
		82	67/33	24	5
Rh	Carbon^d	100	69/31	1	151
		100	68/32	1	151

Experimental conditions: pure cymene, the catalyst, and room temperature. ^aTurnover frequency (TOF) = number of moles of consumed cymene/(mole of catalyst) time of reaction; ^b10% wt; ^c0.2 mmol/g; ^d5% wt; ^e1% wt.